1. Field of the Invention
This invention relates to drive devices having co-ordination control of, for example, a servo motor and other instruments.
2. Description of the Related Art
This kind of drive device has been known as applied to apparatus, for example, of the type in which the servo motor is used for rotating a magnetic disc, and the other instrument is a data write-in/read-out device having a pulse motor for driving the head. As such a device, mention may be made of:
(i) The servo motor and the step motor were controlled by respective individual control systems.
(ii) In case when a microcomputer was used to control both servo and step motors, for the clock was made common with the internal one of the microcomputer, a novelty or limitation on software was prerequisite.
(iii) If, as shown in FIG. 7, a single control system 162 was used for controlling both a servo motor 152 and a step motor 158, a timing signal generating circuit 164 for driving the step motor 158 was provided separately and, for control of the step motor 158, the processing of control of the servo motor 152 was interrupted with its intermediate state stored in a data retreat register 165. After the termination of the control of the step motor 158, the data retreat register 165 was then read out to proceed with the processing of the servo motor 152.
In the conventional techniques as shown in the above-described paragraphs (i)-(iii), however, there have been drawbacks of resulting in a complicated computation algorism and, because of the necessity of using the data retreat register, involving a large increase in the complexity and size of the device.